I started at 12.... in 1968 just after my folks got divorced and we'd moved from Monterey to Chico.
A neighbor kid had a step-thru Honda 55 that I was always helping get running, push starting, etc. Took my first ride on that bike, and when he decided to sell it and get a bigger bike (S90), I wanted to buy it with my paper route money.

My dad figured he could kill two birds with one stone. Make his son the happiest kid on the planet and piss off the ex by buying me a motorbike without asking her permission

Instead of buying a POS beater Honda, he took me down to White Front (K-Mart of the day) and bought me a new mini-bike. I had that for a few months and found a C110 Honda 50 that I picked up for $50 of paper route mulah. Mo' bettah, real motorcycle

Here at work the other week I overheard some engineers talking about a project in Chico.... flood control study on Lindo Channel - which got my attention.
That was two blocks from the house and where I'd take the mini-bike and the Honda 50 after that, to learn how to ride, crash, get up, and go again.
My first big off happened there....My Kawasaki C2 T120 Roadrunner came down after catching big air (a foot or two ) and one of the rear shocks broke - pitching me over the bars. I was trying to keep up with a hotshot on a Harley Baja 100 (Aermacchi smoker).